This project involves the conduct of therapeutic clinical trials for the treatment of inherited immune deficiencies using hematopoietic stem cell transplantation. We previously reported the successful use of non-ablative conditioning to achieve successful long-term engraftment and cure of CGD patients using HLA-matched sibling donors as the source of the hematopoietic stem cell graft. One of the problems with this approach was the high rate (30%) of graft failure or very low engraftment. In 2004 we performed a follow up transplant on an X-CGD child previously transplanted by us who had achieved high level donor T cell engraftment but less than 1% long term myeloid engraftment. We demonstrated successful permanent conversion to almost 100% donor chimerism in the lymphoid and myeloid lineages using conditioning with only busulfan at 10 mg/kg. This strongly supports the use of this approach to rescue low engraftment rather than using a fully myelo- and lympho-ablative conditioning regimen for such salvage therapy. In 2007 we initiated a clinical protocol using busulfan, Campath and low dose TBI and treated 44 patients with CGD, 39 of whom received an unrelated donor graft. and the results were recently published in the Journal of Clinical Immunology. (Parta et al. JCI). Overall our results for the CGD patients in particular are especially promising with an overall survival of 38 out of 47 and an overall long term engraftment rate of 35 out of 38 evaluable. We are also the only centre to have transplanted patients with the P40 form of CGD demonstrating complete reversal of refractory colitis in this unique subset. In follow up to that study we have opened a new protocol modeling on our previous results using a higher cell dose and post-transplant cyclophosphamide to mitigate the increased risk of GvHD from the higher cell dose. At this point, we have enrolled 12 patients on this protocol with two patients dying due to progressive pulmonary disease. Patient one died 2 days after receiving his cells due to progression of his underlying pneumonitis and pneumonia. Patient 8 died 27 days after cell infusion with multiorgan failure secondary to engraftment syndrome overlying progression of his pulmonary disease. One patient did not receive the post-transplant cyclophosphamide due to a low cell dose and although he had initial engraftment, he eventually lost the graft at day 85. He remains alive and well. The most recent patient to be transplanted has developed engraftment syndrome but appears to be slowly recovering. The remainder of the patients have all done well with only one patient to date developing grade1 GvHD and this was limited to the skin. At the end of 2014, we also initiated a clinical trial using haploidentical donors and transplanted a patient with no matched donors available. This patient had an ongoing infection refractory to all standard therapy involving the heart and we therefore proceeded with a parental graft and using post-transplant cyclophosphamide. We obtained good engraftment with only limited graft versus host disease. This patient is now almost 2 years out with complete resolution of his infection and has been described in publication. (J Clin Immunol. 2015 Oct;35(7):675-80). We enrolled a total of 7 patients on this protocol but experienced severe GvHD in the last three patients with two of the patients succumbing to complications related to GvHD. The third patient is doing well having recovered from the GvHD. This protocol is now closed and a new protocol has been proposed using both early and late Campath along with the busulfan and TBI as used in our other transplant protocols along with post transplant cyclophosphamide. The protocol is in the midst of regulatory review but should start accruing by late fall/early winter. In order to determine the outcomes of transplant for CGD in general, we have become a part of the Primary Immune Deficiency Treatment Consortium ( J Allergy Clin Immunol. 2014 Feb;133(2):335-47) and have initiated a collaborative protocol to review the results of transplant done for CGD in North America. We have enrolled over 100 previously transplanted patients and have presented data on a subgroup of patients with inflammatory bowel disease at both the ASBMT and the CIS meetings. A manuscript is now in preparation. We have also been obtaining stool samples pre and post-transplant for microbiome analysis, which is a substudy being done in collaboration with Emilia Falcone (NIAID) and Julie Segre (NHGRI). This data will be presented at ESID this October and a manuscript is also in progress. In related laboratory pre-clinical studies, we have been investigating the use of an adenosine A2a receptor agonist to prevent or treat graft versus host disease (GVHD). Prior studies have shown that agonists specific to this receptor improve outcomes in ischemia models of tissue damage. We have seen benefit in attenuating the onset and severity of GVHD in our F1-parental transplant model and have published this data in the Journal of Leukocyte Biology. Further studies have shown a role for T regulatory cells (Tregs) as part of the mechanism of the drugs effects. We have now established a CRADA with Inspyr Therapeutics (formally Adenosine Therapeutics/PgxHealth/Forest Labs/LNC pharmaceuticals) to study other formulations of the A2a receptor agonists and have seen similar effects on Tregs, both in vitro and in vivo, by these agonists. This data was published in the Journal of Immunology (J Immunol. 2013 Jan 1;190(1):458-68) More recently, we have published a new method to assess these agonists in a more rapid and efficient manner prior to beginning in vivo murine studies (Sci Rep. 2017 Mar 20;7:44816). We also had a collaboration with Gabriel Dvesklar of UHSUS to study Pregnancy Specific Glycoprotein -1 (PSG-1) as an immunomodulator and a possible therapy for GvHD. Preliminary in vitro and in vivo studies have been promising with reduced GvHD seen in our mouse models treated with the protein. Dr Sharma has presented some of this data at the annual American Society of Hematology (ASH) meeting and we have published one paper with some of our analysis of these compounds and a second manuscript is in preparation regarding its use in our GvHD murine models. (PLoS One. 2016 Jul 7;11(7)) We have also been evaluating some of the effects of GvHD on the brain in a project involving, Sarah Bryant, an IRTA who worked in the lab until last summer and who presented this data at the ASH meeting in 2017. Finally with a new post-bac, Caroline Kreitzer, we are finishing up some of the A2A work, hoping to use a rhesus model to further establish their efficacy. Morevoer we are evaluating the role of the thymus in GvHD development and assessing thymic pathways to to target to prevent GvHD and promote thymic regeneration.